Well, this doesn't help 
Article - Many e-cigs' labels show wrong nicotine content, Salt Lake County Health Department study shows | The Salt Lake Tribune
Study: Ow.ly - image uploaded by @SLCoHealth (SaltLakeCountyHealth)

Researchers found that 61 percent of the e-cigarettes they bought at 14 vape shops and 16 tobacco specialty stores had nicotine levels at least 10 percent higher or lower than the label showed.
The industrys own American e-liquid Manufacturing Standards Association requires that nicotine content be within 10 percent of the labeled content, the health department said.
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Seventy-three of the 120 samples had nicotine content that veered from its packaging by as much as 88 percent less than the label to 840 percent more.
Article - Many e-cigs' labels show wrong nicotine content, Salt Lake County Health Department study shows | The Salt Lake Tribune
Study: Ow.ly - image uploaded by @SLCoHealth (SaltLakeCountyHealth)